Railway signaling system



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i een l cuit" over which cver"`the lme circuit.

Patented Nov. 214, 1944 j f l fegato?? itnllpufnxt siGNAN'G SYSTEM Crawford E. Staples andHerman G. lsser,`

l "Pittsburgh, Pa`",^assgnors to Tli"Unibn"SWi'tch` Signal Company, Swissjale, Pa`., a corporal l `tion of Bennsylvania flilnlrttioll lult 24,1943;

latte t t 13 claims. (alitalia-#39) f t Olll llllfellllllll rtlttlttitel. elle@ ftllllt'y s lg.-

` 'current by tlelllttsllltll# ""t the trali sectioiisle uiV track circuits" ifra sit `Afurther` "inject of the inv eilt line' tilcult at tnttlilettf th ett redire the bien l must pe transmitted amount 'of energy "andi preventing interference by the coding relays with thejfoperation of each otiien Another object Gf the. inlfentoll isf t0. provide means of the type Vcl esc'rbed which is arranged so 1n Such situations' it hasfben ppsd tofftransdf these llllly t0" th fall'str `coded alternati'rliwgcurrenti meansfoer- `ated by coded energj'suppl cuit extending around the that. thetlatk relays fitllevarllls ttf-itk sections i `rtoritrjol connectigdptthe' o o mgritystwith the une circuit. so that as atr'stntnte'rs each track section the line circuit is connected tothecoding relay associated with that tracksetipn and `is disconnected from' tlieodingrelays lfprthe track sectionsntherear. t t A further object ofthe invention is top rovide anfirnprOi/eljytem -n t chl" fltltttl togdlel is. transmitted over a une circuit and which incontrolle catedat the "end of 'this line crciti'energized stretch inthereanwhilemeans is `provided for supplyinghfeed-back "energy over, the line circuit to controltfunctions at the exit end of theblock following relay` is occupied the supply of coded energy over the line circuit to the first code following relay is copriectedto the line circuit and occupied track section, while `thesupply of Afeed- `In some species of the invention tliejnductance f olfthe code following relay is vsuch that the puise ofenergy inducedrin the relay Winding on of this energy for this purpose eliminates the need for an impulse relay and associated apparatus to control the supply of feed-back energy to the line circuit.

We shall describe one form of railway signaling system' embodying our invention, together with several modifications thereof which We may employ, and shall then point out the novel features thereof in claims. i

In the drawings,

Fig. 1 is a diagram of a stretch of railway track equipped with a signaling system embodying our invention, and

Figs. 2, 3, 4 and 5 are fragmentary diagrams showing modifications which we may employ.

Similar reference characters refer to similar parts in each of the several views.

Referring to Fig. 1 of the drawings, there is shown therein a stretch of railway track having trackrails I and 2 over which traic normally moves in the direction indicated by the arrow, that is, rfromleft toright.A `The rails of the track stretch' are divided by insulated joints 3 into block sections for signaling purposes. One complete block section, togetherwith portions of the two adjoining block sections, is shown in the drawings. f .i

The block section shown in thedrawings includes ran intersection with a highway R, and the railsof the block section are divided by insulated joints 3 into track sections to provide `for control of the crossing signals XS which warn users of the highway of` the approach of a train. As shown, there are track sections 1AT, 1BT, TCT and TDT, the section ICT being a short section which includes the highway crossing and is provided-so that on movement of a train in either direction through the track stretch operation of the crossing signals will be continued until the train clears the crossing. `If this method of con- .trol-,of the crossing. signals'is not required, the section 'ICT may be omitted and-the sections 'IBT I and lDT may adjoin.

A -wayside signalI designated S with an appropriate numerical prefix is located at the entrance end of each block section. These signals vmay be of anyappropriate type, and as shown are of the color light type, each signal having a green or proceed lamp G, a yellow or caution lamp Y, and a red or stop lamp R. While the invention is illustrated yand described in connectionwith a track stretch equippedwith wayside signals, the invention is not limited to use in such situations, but is equally applicable to track 'stretches without wayside signals and in i which traffic is governed solely by cab signals.

The block sections 6Tvand 8T may be equipped with coded track 'circuit apparatus of any appropriate design. One form 'of'apparatus which may be employed in these sections is shown in our application for Letters Patent of the United States Serial No."473,'792, filed January 28, 1943.

Similarly,the section 'IAT may be provided with coded track circuit apparatus of the type shown in our application identied above. HoweverQif` desired, the track section TAT may be provided ywith track circuit apparatus of the type employed in sections lBT and 1DT and described inr detail below.

The track sections v'I BT, 'ICT and 'IDT are provided with track circuits employing steady or non-coded energy, Each of these sections has a track batteryconnected across the section rails at one end of the track section, and a track relay, designated TR with an appropriate prefix,

connected across the section rails at the other end ofthe track section.

In addition, each of the track sections 1AT, 1BT, 'ICT and 'IDT is provided with a track transformer designated TT with an appropriate prefix. The track transformers are located at the exit end of the associated track section, and each of these transformers has its secondary winding included in the track circuit of the p associated track section.

the United States Serial The track batteries for track sections IAT and 'IDT are located at the exit ends of these sections and the secondary windings of the track transformers for these track sections are connected in series with the track batteries.

The track relays for sections 'FBT and 1CT are A located at the exit ends of these-sections, and the secondary windings of the track transformers forfthe'se sections are connected in multiple with the track relays. A resistor isincluded in series with' each of the transformer secondary windings to reduce flow of direct current track circuit energy through the transformer secondary windings, while the windings ofthe track relays have such high impedance to alternatingcurrent that little energy supplied from the track transformers flows through the relay windings. The highway crossing signals XS are controlled by relay XR which is governed in the manner well known in the Yart by slow releasing relays WS and ES, and by the track relays 1BTR, 'ICTR and 1DTR.

The operation of Arelays XR WS and ES to trol the crossingfsignals `XS is not a part of this invention, and in order to simplify the disclosure their operation will be omitted. A description of the operation `of these relaysmay befound in application for LettersPatent of No. 463,733 of James J. Van Horn.

A pair of line wires l0 Vand Il extend from the exit-end of the block section tothe exit end of track section 1AT, while means is provided for supplying master code and feed-back energy over this line circuit to control the supply of coded alternating current cab signal enelgy to the rails of thecvarious track sections and toalso `control the supply of coded track circuit energy to track section 1AT.

A coding relay CR is located at the exit end of Vthe block section and controls the supply of master code to the line wires Ill and Il, connec tion of line wires I0 and Il to the line winding of feed-back detector relay AR, the supply of energy to the local winding of relay AR, and the supply of energy to the primary winding of track trans former 1DTT.

Means governed by trailic conditions in section 8T is provided for supplying coded energy to coding relay CR. This means includes a relay 8H which is controlled by traii'lc in section 8T so that its contact I2 is picked up or released according as section 8T is vacant or is occupied. When contact I2 of relay 8H is picked up it establishes a circuit controlled by a contact of code transmitter |8DCT for supplyingA energy to coding relay CR so that at such times relay CR is operated at the code speed. When contact l2 of relay 8H is released it establishes a circuit controlled by a contact of code transmitter 'I5CT so that at such times relay CR is operated at ,the 75 code speed.

The relayAR controls the supply of energy to slow releasing relay AP which governs the circuit 21 to be moved to the pbsinon in which it interrupts the circuit of relay AP. The relay AP is of periods in which the supply of energy to the relay f winding is interrupted. Accordingly, contact `33 of relay AP interrupts the circuit for supplying energy to the lamps of signal 8S, whilecontact 34 of relay AP interrupts the circuit of the primary Winding of track transformer 'IDTT.

In addition, on release of the contacts cf'relay CRA, the supply of energyv from battery IATB to the rails of section 'IAT is cut off, while the track winding of relay ARA is connected across the rails of section IAT. On interruption of the supply of energy from batterylATB to the section rails the contacts of the track relay IATR release and an impulse of energy is supplied from the decoding transformer IDT torelay 'IIR to pick rup the contacts of this relay momentarily and thereby cause an impulse of feedback energy to be supplied to the section rails. `This energy feeds over back contact 22 of relay CRA to the track winding of relay ARA and causes contact 2li of the relay to move to its normal position to establish the circuit of relay APA." The relay APA is of a type the contacts of which are slow to release so its contacts remain picked up during the periods in which the supply of energy to the relay winding is interrupted and contact 35 prevents the supply of alternatingcurrent to the track transformer IATT and shunts the primary winding of the track transformer to thereby reduce vimpedance of v`the transformer secondary winding and reduce arcing at thev contacts of relay CRA. v n

In addition contact 36 of relay APA maintains the circuit for supplying energy to the primary winding of impulse transformer IT so that the impulse relay IRA is operated to supply feedback energy to the line wires III and II.

As a result of code following operation of relay 'IATR energy is supplied through the decoding transformer IDTr to relays 'IAI-I and 'IAJ and they function in the usual manner to control the supply of coded energy to the rails of the adjacent track section in the rear and to control:

the signal 1S.

As long as the block fore, relays APA and AP are picked up to pre- 'vent the supply of alternating current to track transformers 'IA'IT and 'IDTT, while relay CRB is released and prevents the supply of energy to transformers 'IBTTand 'ICTT.

Operation of equipment on movement of a train through the track tion When a train moving in the normal direction of trac enters section 'IAT track relay 'IATR is shunted with the result that relays 'IAI-I and 'IAJ release, while relay 'IIR ceases to operate to supply impulses of feed-back energy to the rails of section IAT. When the supply of feed-back energy to the rails of section 'IAT is cut off the contact 24 of relay ARA is moved to its righthand or reverse position by energy supplied to the local winding of the relay and it thereafter remains in that position so that thecircuit of relay APA is interrupted. Accordingly, contact 35 of relay APA releases and alternating current energy is supplied to transformer ,IATT and thereafter energy is supplied from this transformer to the rails of section 'IAT during each section is vacant, theref stretch in the 'normal direcpicked-up period of the contacts of relay CRA. At this time the relay CRA continues to besupplied with coded energy of y code frequency so the alternating current energy supplied tol the rails of section 'IAT is coded at this rate and will operate the cab signal apparatus on the locomotive to provide the clear indication.

In addition, on release of relay APA its contact '36 interrupts the circuit of the primary winding of impulse transformer IT so that energy ceases to be supplied through this transformer to relay IRA, and the contacts obf relay IRA remain released with the. result that energy are nolonger supplied to the line wires I0 and II. Accordingly, contact 21 of relay AR is moved to energy supplied to the local winding of the relay and remains in that position so that the contacts of relay AP release, and contact 33 establishes the circuit of the-lamps of signal 8S, while con-5 tact 34 establishes the circuit of the track transformer 'IDTT. The circuit for supplying energy to the track transformer 'IDTT includes contact 31 of relay CR so the alternating current supplied to the rails of section 'IDT is coded at the rate determined by the rate of operation of relay CR.

When the train advances into section IBT track relay 'IBTR releases and its contacts 38 and 39 cut off `the supply of master code energy over line wires ID and I I to relay CRA and connect wires I 0 and II to the winding of relay CRB. Accordingly, relay CRB is operated by energy of 180 code frequency supplied over line wires I0 and I I and on each movement of contact 40 `of relay CRB to its picked-up position energy is sup-I plied over front contact 42 of track relay 'ICTR to transformer TBTT to thereby cause coded alternating current to be supplied to the rails `of section 'IBT to operatethe cab signal apparatus on the locomotive while the locomotive is in that section. K i

In addition, onv release of relay IBTR and re-k sultant interruption of the supply of energy to f relay CRA the contacts of this relay remain released so that coded energy is no to the rails of section IAT.

When the train advances into section ICT- track relay ICTR releases and its contact 42 interrupts the circuit of transformer 'IBT'I' and longer supplied establishes the circuit of the transformer 'ICTT l so that coded alternating current energy is supplied to the rails of section ICT to operate the locomotive cab signal apparatus while the locomotive is in section 'IC l In addition, when track relay v'IC'I'R releases its contacts 48 and 49 connect line wires IIJ and II directly to the coding relay CRB and thereby insure that as long as section 'ICT is occupied the' relay CRB will be operated b-y coded energy sup' plied over the line wires. At this time contacts 48 and 49 of relay 'ICTR prevent supply of energy overline Wires I0 and II to relay CRA so that relay CRA remains released and does not supply coded energyto the rails insures that signal 'IS willcontinue to display its stop indication and that enters `section IAT the cab signal 'equipment on the locomotive will display its'stop indication. l When the train advances into section IDT relay -'ID,IR releases and its contacts 52 and `53 interrupt line Wires I0 and II to prevent the supply of coded energy relayCRA or CRB.

As previously explained, when the train entered impulses of feed-back its right-hand or reverse position by of section IAT. This' if a' second locomotive' over these Wires to either` From the `foregoing it willbe seen that when the track stretch is vacant master code energy is supplied over the line wires II] and II and operates relay CRA to supply master code to the rails of section TAT, while as long as the block section is vacant feed-backenergy supplied over the rails of section TAT operates relay ARA to energize relay APA so that it prevents the supply of energy to track transformer TATT and maintains the supply of energy to impulse transformer IT so that relay IR is operated to supply feedback energy to line wires I and I\| and thus operate relay ARand energize relay AP to prevent the supply of energy to track transformer TDT'I and to the lamps of signal 8S. In addition, 1

when the block section is vacant track relays f TBTR and TCTR interrupt the circuit of relay CRB` so that itsH contact interrupts the supply lof cab signal control energy to `sections TB'I and TCT. t

'When'ai train enters section TAT the supply of`feed-back energy over the vrails of section TAT isvcut off and relay'APA releases to cause cab signal control energy to be supplied to the section rails, and to cutoff the supply of feed-back energy to "line wires I0 and II so relay AP releases and causes the signal 8S to be lighted ated by both master code and feed-back energy supplied over the line circuit. When the con'- tacts of relay CR `are picked up master code energy-is supplied to the line wires I 0 andTI and operates relays CRA and AR. The polarity of the energy supplied to the line wires is such that master code energy supplied to relay AR causes the relay contact 2T to be moved to its righthand or reverse position in which it interrupts the circuit ofrelay AP.

On release of the contacts of relay CR the supply of master co-de energy to the line wires is cut .off while connection is established between the line `wires so that on picking up ofrelay IRA,

and causes cab signal control energy to be supp plied to the rails of`section TDT.

When' the train advances into section TBT track relay TBTR releases andinterrupts the supplyof energy from line wires I0 and II to relay CRA and connects'line wires IIJ and II to relay CRB. Accordingly, relay CRA ceases to follow code so that coded energy is no longer supplied to section TAT, while'relay CRB is now operated so'that coded energy is supplied to section TBT or section TCT.

u It will be seen that the apparatus is arranged so that the coding relays CRA and CRB are not both connected to the line wires I Il and II at one time. As only one coding rel-ay is connected to theline wires IIl'and II at one time operation of the coding relays is positive, and these relays can be operated over relatively long line circuits with a minimum of' line current. In addition', as only one codingV relay is connected to the line wires at one time there is no possibility that the coding relays will interfere' with each other. Accordingly, thecoding relays will accurately respond to the coded' energy supplied over the line wires and will cause 'coded energy of accurate code pattern to be supplied to the rails of the track sections. i

Furthermore, as coding relay CRB is not con nected tothe line wires when coding relay CRA is being operated by venergy supplied over these wires, there is no possibility that relay CRB will interfere with the impulses of feed-back energy supplied to the line Wires as a result of operation of relay CRA.

Modification Vshown Fig. 2

In the system show'n in Fig. '1 thevrelay AR is provided with a local winding which is energized by current supplied over `a local circuit when relay CR is picked up, while relay AR is provided with a separate line Winding which isv connected and resultant supply of an impulse of feedhack energy to the line wires, this energy will flow through rthe winding of relay AR. The polarity of the feed-back energy is such that it causes contact 21 of relay AR to move to its left-hand or normal position in which it establishes the cirl cuit ofV relay AP.

As long as the block section is vacant so that feed-back energy is supplied over the line wires I0 and II relay ARk operates to maintain relay AP picked up and thus prevent the Supply of cab signal energy to section TDT and to prevent the supp-1y of energy to the lamps of signal TS.

When the block section is occupied the supply of feed-back energy over the line wires. I0 and f I I is cut off and master code supplied to the line wires holds contact 2T of relay AR in its reverse position in which it interrupts the circuit ofirelay AP so relay AP releases.

` The equipment is otherwise the same as that shown in Fig. 1 both in construction and operation.

Modijcatz'on shown in Fig. 3

If desired the coding relay CRA may be connected in series with the line circuit, and Fig. 3 is a fragmentary diagram .illustrating such a modication.

As shown `the relay CRA is connected in series With line wire I I, While this relay is of a type the contacts of which will pick up when and only when energy flows through the relay winding from right to left. Contacts I4 and I5 of relay IRA, when released, establish connection between the line wires III and I I so that on the supply of master code to the line Wires this energy can flow through the winding of relay` CRA and operate the relay. On release of relay CRA and consequent picking up of relay IRA, feed-back energy is supplied to the line wires II) and II in series with the winding of relay CRA, while thedirection oi flow of feed-back energy throughthe relay CRA is such that it is ineffective to pick up the relay contacts. i

The modification shown in Fig. 3 is applicable to the species shown in either Fig.l 1 or Fig. 2.

Modification shown in Fig. 4

IU and II. The apparatus of Fig. 4 is otherwise the same as that shown in Fig. 1.

In operation on picking up of the contacts 20 and 2l of coding relay CR energy is supplied Wires LI and; I I moves l ARHto its right-hand orreverse position and picksI aerienne! over the. Lline Wires l llene l I texthe reley AR and CRA. This energy uis of o l-such `polarity that it lilleleftemeverwes IIl and Ilvfte relay causes the coritacii'l4- of relay lAR` to moveto `its contactsof relay CRA to pickup. 4 i

l On release` of the contacts o'f relayCR the supply of energytotheline wireswlljand II fand to the relays CRA ,ando-AR is cutoff` `and theeontacts er "the" reiay` CRA` release, while the aux the ogres of the relays CRA and AR collapses, thereby inducing inthe relay windings an impulse of energy which` is of suchpolarity that energy continuesto flovv` in the sameedirecton that it had been llewlne belel'eih'e, Supply el energy te the rfeley winding was interrupted- `leeeldleely,the

right-hand on reverse positiomwhile it causes the indueed the relay winding and is Supplied l 1L relayAP is employed only to c ontry portioned so that the impulse of energy supplied f energy suppliedrfrom relay CRA, Accordingly, i

energyinducedin the Winding of relay AR'lows from right `to left, while theenergy induced in relay CRA also flovvs from right to left. y o

this timethe windings of 'relays 4and ARmare connected in series and `energyinduced in the Winding `of one or "these relays `news through lthe winding ofthe other relay.l `The energysuppliedyfrom relay CRA Lto relay AR flows through-the winding of relay AR 'from leftto` right and thus tends` to move thecontact v2'I `of releyzlllwree ltereveree te its nermel Deeltlell 'In'he relays CRA and AR and the otherportions O fftlle eemblnetlenere erlepetlened Se that the impulseof energy supplied Vfrom relay CRAIto relay AR on` interruption of the supply of energy to the line Wires isA of such 1value as to movethe eontact ofrelayAR to itsnormal position, While the relay AR is of `suchclesign that ite` contact,I when moved to either position', remains in that position until energy of the `polarity effective to move the relay contact `toits other position is sup-- plied tothe relay Winding; o 1

Thejimpulse of `energy induced in the 4winding of relay AR on interruptionlof thesupply of energy to line wiresIILand II" is supplied tothe winding `of relay CRA and Aflows through this Winding from left to right. The relays AR and CRA may be so proportioned that 'the impulse of energy supplied from relay AR to relay C13-Agis too Asrnallfin valueto operatetherelay CRA while the relay CRA mayy be" of.. the polar biased type the contacts offyvhich when released Willpickup only-When energy flows through the relaywinding `IOI'ILrght to leftfthat isinthe opposite direction to thatf the energy supplied from the relay AR.

lll', Will therefrom `to relayMAR will operate relay AR in the Seme `manner that relay A Rwes opera-ted by vhenrelay 'IBIR releases and transfers connection of ,line wwires Ill and II frornrelay CRAto `relay(1)1351?,the relaylAR continues to operateand,

maintainzrelay AP picked up. o i

Ifmrelay Al? is employed to control the supply of energy tothe lampsof signal 8S itmay `be preferred to have the relay AP" release as soon as C section 'IBTisoccupied n,Ifmthi'smethod` oi oper-- ationis desiredv therelaygCRBmay be proporreI `tioned so that the impulseA of energy suppliedltherefrom te relay `AR on :interruption of the Supply ef ellerey te line Wree 'aand Il `is of teo Small/7941116 to operate the relay.` Accordingly,` when relay lB'lltreleases` and transfers connec-` tion of theyline Wires Illand IIfrom relay CRA to relay CRB energy for `moving the contact of relay `AR to its normal position is no longer supplied torelay AR and itsveontactfl]remainsin its reverse position andrelay AP releases. "Whenthetrain advances into sectionlJQ'l track relay lDTR releases and uits contactsql l and53l1interruptthe linefwires Illmand I I toont be seenfthat each; time thecontaczts` of,

relayCR are closed energy suppliedrto jthellline"` f the `contaet `2T` of relay up the contactsof relayl CRA. `Each`time` the contacts of relay CR release the contacts of relay CRA release, While energy inducedlvinthe Windmeer relay CRA is supp1iedhto` reiaygAR and moves "contact 21 of the relay from yits rightmainsllpickednup, While relay CRA is operated by Vcoded energy.

`When a train advarfeesifnto section JTtrack rei' y WBTR releases and its' contacte` se and `as, circuit of relay CRA and connectv interrupt the line wires L0 and I ItorelaylCRB, RelayCRA,

therefore, ceases to `felloiif code, While 'energy froxn-thefwindiguf this relay is'no longer Sill)-` piieeroeiaynm n o u 2 After releaseof relay wlBrljRrelay CRB 1s op- `supplied tothe line Wires elated tyjeededjener Luanat een eeezereefeeeeeeleeeee @e ell-ee i r [,whil ach'nmetne supply/of energy hand to its left-hand position. Ac'cerdirifglyL'a'sr l long as theblock sectionis vacant relayAP reoff thesupply of master code over these line wires, andtofalsoyeut eff the SuppIy of impulses o of feed-back energy over the line 'Wires IIJ land II to the-relay AR so thatitceases to establish the circuit for relay AP and its contactsl release if they have not already done so.

`When the block section vis vacated master code is again Supplied `over line wires I0 and. II -to relay CRA and it operates to supply coded energy to the` rails of section TAT; whileaimpulsespl feed-back ,energy are supplied over line wires o I0 and II to relay AR to operate `it and energize therelayAP. o i l l lillohe operation of thesystem shown in Fig: 4

is substantially the same as that shownV in *Fig 1 except thatI in the system Vshown in Eig.` ll the supply ofV feed-back energy over the line wires I0 and `II is not cut; `off when a train enters section 'IAT, but is maintained at least until section r'I B'I is occupied. l i

Modifcationshow in Eig. `5 =In the arrangement as shovvnin l the supply of `feed-hack energy over theline Wire I0 -a-nd'll is cut 01T as soon as atrainenters'sec- `tion TAT. This insures that the lamps of lsigrialS Will'he lighted as`so`n` asta` trainehters' the adjacentfblock section `inthe rear,-but it also i causes alternating current `:energy to vhe surmliecltciI the rails of section lDTassoon as; section IAT is occupied. It may be desired to have the lamps of signal" 8S lighted 'as-"soon-as sectionl'IATis occupied,` `but to defer thesupply of y,alternating current energyfto `seetion `TDT until' the train enters that sectionyuand the modieationshown in Fig. 5 providesfo'r this` method The modification shown in Fig. 5 has two 4feedback detector relays. These fare `relay ARN,

o which `isoperated by feedfpack energy of normal i pdarty. and relay einen, which -isfeeerated by the Supply yof alternating current eab 4signal con# trol ,energy to thefrails of section 1D?, it is 11no necessary to have this relay release when section o 'IRT isl occupied and the relay CRB may he pro" TDTT.

feed-back energy of reverse polarity. The relays ARN and ARR are of the polar biased neutral type the 'contacts of Which pick up'- only when energy of a particular polarity is supplied to the relay. The relays ARN and ARR havel line windings which are connected across the line Wires l and ll in series'when the relay-CR is released, while each of these relays has a holding Winding to which energy is supplied when the relay'contacts are picked up'and the contacts of relay CR are released. The relay ARN controls the supply of energy to slow release relay APN,' and relay ARR controls the supply of energy to slow release relay LAPR.

The relay APA, which is governed `by feedback energy supplied over the rails of section 'IAT controls the polarity of the feed-back energyv supplied to line Wires l0 and Il on operation` of yrelay IRA so that energy of `normal' or reverse polarity is supplied according as relay APA ris picked up or released.

The coding relay CRB has associated therewith feed-back supply means includingfan impulse transformer ITB and an impulse relay IRB which operate to cause impulses of feed-back energy of reverse polarity tobe supplied to the' is operated v line Wires I0 and Il when relay CRB by coded energy.

The equipment for section TAT is the same in.

kconstruction and operation as that for thecor-' responding section of the system shown in Fig. 1.

The equipment of Fig. is shown in the condition Which it assumes when the track stretch is vacant. At this time energy of 180 Acode fre quency is supplied to the coding relay CR, and' When its contacts are picked up energy is supplied over front contacts 20 and 2| to line wires Il! and il, from which it is supplied over back contacts I4 and I5 of relay IRA to relay CRA. The relay CRA, therefore, operates to cause energy to be supplied to section 'IAT so that feed-back energy is supplied over the section rails to' operate relay ARA and'maintain the contacts of relay APA picked up so that the feedback energy supplied to the line Wires I0 andv H is of normal polarity.

On release of the contacts of relay CR the relays ARN and ARR are connected across the line Wires I0 and Il, While relay CRA releases andrelay IRA picks'up to cause an impulse of feed-back energy of normal polarity to be supcontinues to operate afterrelease of relay'APA.

On the supply -of feed-backenergy of reverse polarity to the line Wires pI/ andY l I- relay ARN l ceases to operate, While relay'ARR now oper- 'soA ates. Accordingly, relay'APRpieksup and relay APN releases, and the operating' times of the relays APN and 1 ARN are such' that APR picks up before ARN releases. i

On release of relay APN its contact 62 establishes the circuit forfsupplying energyto the lamps of signal 8S so this signal is-lighted and provides an indication oftrafc conditions in advance. On release of relay APNr its-l back contact 63 is closecLVbut the circuit of the ltrack transformer IDTT is interrupted'by front con-` tact 65 of relay APR so energy is not supplied to the tra-ck transformer IDTT atthis time. This is desirable since section TDT ist not occupied'lanfd it is unnecessary to supply calo signal control energy to the rails of this section until the section is occupied.

When the train advances into section -IBT track relay 'IBTR releases and its contacts `38` and 39 cut olf the supply of venergy over line wires I0 and Il 'to relay CRA and connect line Wires I0 and Il to relay CRB. Accordingly, re-

lay CRB noW operatesy and causes coded, alternating current to be supplied to track transformer 1BTT, as explained `in connection With the system shown in Fig. 1 of the drawings. In

addition, on operation of relayCRB energy is plied over the line Wires to relays ARN and ARR.

This impulse of energy picks up the contacts of` relay ARN and its contact 60 establishes a circuit for the relay holding Winding. This circuit includes back contact 26 of relay CR- and keeps the contacts of relay ARN picked up until the coding relay contacts pick up. When relay ARN picks up its contact 6| establishes the circuit of slow release relay APN f and its contact 62 is picked up to interruptthe circuit of the lamps of signal*v 8S, while its contact 63 interrupts the supply of energyto track transformer On continued coding operation of relay CR relays APA and APN are maintained picked up, While at this time relay CRB is deenergized.

When a train moving in the'normal direction of traffic enters section IAT the supply of feedback energy ove'r the section rails is cut off and relay APA releases and changesthe feed-back energy supplied to line Wires l0 and Il from normal to reverse polarity, while it also establishes the circuit yof the track transformer IATT so that cab signal control energy is supplied to the supplied through an impulse transformer ITB to an impulse relay IRB and it operates to sup-i plyimpulses of feed-back energy of reverse polar-VV ity to the line Wires l0 and Il from a suitable source of current, such as a battery. The yfeedback energy of reverse polarity supplied to theVVV line Wires l0 and Il operates relay `ARR yand maintains relay APR energized to thereby prevent the supply of energy `to track transformer IDTT. i

When the train advances into section 'ICT track relay 'ICTR releases and its contacts48and 49 connect line Wires I0 and Il to relayV CRB so that relay CRB continues to operate and feed-r .back energy continuesto be supplied to thle'line Wires I0 and Il so that relay APR is maintained energized and prevents ythesupply of energy? to track transformer lDTT. In addition, as explained in connection with the systemV4 shown in Fig.1, on release of relay TCTR the `supply .of` energy to transformer IBTT is cut 01T, While en-` ergy is supplied to transformer lCTT.

When the train advancesl into section 'IDT' track relay 'IDTR releases and its contacts 52,v

and 53 interrupt the line lv'vires l0 and `Il so that relay CRB ceases to follow codeand the supply of `feed-back energy over the line Wires to relay ARR is cut off. Accordingly, relay APR releases and establishes the circuit of track transformer 'ID'IT so that coded cab signal control energyyis supplied to the rails of sectionj'lDT to operate the cab signal apparatus that section. I v e When the train vacates block section 'lTthe track relays for the sections TB'IY, .TCT and lDI' pick up andr establish the circuit ofthe line Wires Ill and Il with the result that `relay CRA operates to supply energy to'section TAT,` While feedback energyof normal polarity is `supplied over the line Wires andoperates relay ARN `to pick up. relay APN and cut 01T the supply of energy to' on the locomotive `in* that section is occupied.

"spirit andlscope of our invention.

i From the, foregoing itwill be seen that the system shown in Fig. `L operates so that the lamps vof signal 8S are lighted as soon as. atrain. enters the adjoining track section in the rear, but that alternating current cabsignal control energy is supplied to each of the track sections only when In the. systems shown in Figs. 2y and1 5 the other appropriate apparatus well known in the art. n

While each of the rnodicationsl of the invention, has been illustrated and described in connection witha block section` which is divided in an particular manner for the control of the crossing signals, the invention is not limited to` the specific arrangement of track sections., shown,u and it is contemplated that the-track sections may be arranged in other Ways if the location of the highway intersection within the block section makes a dii'ierent` arrangement of the track sections.` necessary or desirable. i Although we have, herein illustrated and described only one form of railway signaling system embodying` our invention,V together with sev-f eral modicationswhich we` may employ, it is understood that various changes and modifications4 may be made therein within the scope` of the appended claims withoutdeparting from the Having thus described our invention, what we claim is v 1.1In combination,a stretch of railway track having trackrails divided by insulated joints 'into arst, a second and a third track section through which are operated in the order named aacaooe the lamps of signal 8S, and to the track trans- `1.0 i means for controlling the highway crossing si'gi i nals is vlnotlshown, but these may be governedby y apparatus similar to` that shown inE'ig. 1,'or1by` t n 49 means including a front contact of a second cod` ing. relay for supplying alternating current to the rails of said second track sectioma third r coding relaycontrolling the supply ci` alternating current tothe rails of said third track section and controlling the supply of coded, energy to` `said line wires, means governed by traic conditions in advance of` said third track sectionior at times `supplying energy of a rst code frequency and at other times supplying energy of( a second code frequency toY said third. coding relay, means effective according `as said second. track section Vis vacant or is occupied to permit energy to he y supplied over said line wires tol said rst or said locomotives equippedwith cab signal apparatus responsive to the flow of coded alternating cur,- rent inthe track rails, a pair of line wires substantially -coextensivewith said second and third Vtrack sectionsa firstcoding relay controlling the. supply of codedA alternating current to the rails of` said ilrst track section, a second coding 'relay vcontrolling the supply of coded alternating second cod-ing relay, and `means effective when saidthird track sectionisoccupied to prevent the, supply of coded energy over said linewires.

3.` In combination,` a stretch of railway track `having track rails divided by insulated joints. into a iirst,` asecond and a third track sectionrtlirougli which are operated inthe order named locomotives equipped with can signal apparatus responsive tothe `flow of coded alternating current, in the track rails, av pair of line wires substantially coextensive with said second and third track seci tions, a first codingrelay controlling the supply of coded alternating, current. to the rails of` said `iirst track section, a second, coding relay controlling the. supply of coded alternating current to the, rails of said second track Section, a third coding relay controlling the supply of coded' al- `ternating.current to thev rails of said `third track section and controlling the supply of coded energy to` said line wires, means governed by traiiic conditions in` advance oi said third track` section for at v times supplying energy of a `first code` frequency and at othertimes supplying energyof a second code. frequency to saidthird' coding relay, means eliective` only when said second section is vacantto'oonnect sai'dlinewires to said rst cod- `ing relay and effective when said second track section is, `occupied to connect said. line wires to current to `the rails of said second track section,

a third fcoding relay controlling the supply. of coded alternating current to the rails of. said third track section and controlling the supply of coded energy to said line wires, means governedv by tratc conditions in advance of said third section for at times supplying energy of. a iirst code frequency and at other times supply-` `ingenergy of a secondcode frequency to said :third coding relay,`means effective according as said second coding relay, means effective, when said lnewires are connected to said iirst coding y relay for supplying feed-back energy to the line wiresin` the intervals between theimpulsesof energy supplied to the line wires by "said thirdv i coding relay,` means effective when` said third track section is occupied to interrupt the circuit `of, said line Wires, and means responsive to feedback energy supplied over said line wiresland controlling the supply of alternating current to said second track section is vacant or is occupied i tonpermit energy to be supplied over said lineI wiresy to` said first or said second coding relay,

and means' effective when said third tracksection I is-occupied to prevent the4 supply of coded energy over said line wires. i

2. In combination,4 a `stretch of railway' track having track rails divided` by insulated joints into a first, a second' and` a third track section tl-nougln` which are operatedV in the order named locomotives equipped with? cab signal apparatus responsive to the flow of coded alternating cur-1 rent iii the track rails, apair of; line wires substantiall-y coextensive with sadsecond and third i track sections, means` including a front contact lci a` rst codingrelay `forsupplying alternating current to the: rails; of-` said rsi; track section;l

the rails of said, third track section t y 4. In. combination, a stretch of railway track` having, track rails divided by insulated; joints into arst,` a secondand a third track section through which are operated in the order named locomotives equipped with cab signal apparatus `responcoding relay cont-rolling the supply of, coded. alterhating current to the rai-1s` of Said' third track section and controlling the. supply of` coded energy to said! line wires, means governed by traic "conditions inladvance of `said third track section for at. times supplying energy of a iirstcode fre-` quency and. `at other times supplying energy of a second` code frequencyto said third coding, re-

]lanmeans effective only whensaid second track 'Wires and controlling the supply of alternating current to the rails of said third track section.

5. In combination, a stretch of railway track 4 having track rails divided by insulated joints into a iirst, a second, a third and a fourth track section through which are operated in the order named locomotives equipped with cab signal apparatus responsive to the iiow of coded alternating current in the track rails, a pair of line Wires f substantially coeXtensive with said second, third and fourth track sections, a first coding relay controlling the supply of coded alternating current to the rails of said first track section, a

second coding relay controlling the supply of coded alternating current to the rails of the second and third track sections, a third coding relay controlling the supply of coded alternating current to the rails of said fourth track section and controlling the supply of coded energyto said line wires, means governed by traffic conditions in advance of said fourth track section for at times supplying energy of a iirst code frequency and at other times supplying energy of a second code frequency to said third coding relay, means effective only when said second and third track sections are both vacant for connecting said line wires to said rst coding relay and effective when said second or said third tracky l section is occupied to connect said line Wires to said second coding relay, means effective only when the third track section is vacant to establish the circuit controlled by said second coding `relay for supplying alternating current to the` Trails of said second track section and eiiective'uf5 only when' said third track section is occupied to lestablish the circuit controlled by said second 'coding relay for supplying alternating current to` the rails of said third track section, and meansL effective when said -ffourth track section is oc-` cupied to prevent the supplyv of coded energyr over said line Wires.V

6. In combination, a first anda second block section of railroad track through which are Y operated locomotives 'equipped with cab signal apparatus responsive to the flow of coded alternating current in the section rails, a signal including a lamp governing entrance of trains into the second block section from the first block sec- Ation, the rails of said iirst block section being `divided into a plurality of track sections includ- "ing a first and a second track section which are track section, a coding relay operated by coded energy lsupplied over said line Wires and controlling the supply of alternating current tothe Arails of said first track section, means governedv by trafc conditions in said second block section lfor supplying coded alternating current to. the

rrails of said 'second track section and for supplying coded energy to said line wires, means for Vsupplying feed-back energy to said line Wires in the intervals between the impulses of energy supplied" to said line Wires Abythe (means gov,- erned by vtraiiic conditionsvin said second block section,.. and means responsive'` tofeed-back energy'supplied over said line Wires and controlling the supply of energy to said signal lamp.

7. Inr combination, a first and a second block section' of railroad track through which are operated locomotives equipped with caloY l,signal apparatus responsive tothe flow of coded, alternating current in the section rails, a signal including a lamp governing entrance of trains into Athe second block sectionl from the first blocksec'- tion, the rails of'said iirst block section being divided into a plurality of track sections includ'- ing afrst and a second track section Whichare traversed in the. order named by a train traveling in the normal direction, a pair of line wires governed by traiiic conditions in said second track section, a coding relay operated by coded energy supplied over said line Wires and controllingfthe supply'of alternating current to the rails of said iirst track section,` means governed by traiiic conditions in said second block section for supplying coded alternating current to` the rails of said secondtrack'sectipnand for supplying coded energy to said liney Wires, means governed by trafc conditions in said iirst track section for supplying feed-backenergy to said.

8. In combination, a iirst and a secdnd block section of4 railroad track through Ywhich are operated ,locomotives equipped with cab signal apparatus responsive tothe iiow vof codedalternating current in the section rails, a signal including a lamp governing entrance of trains into 'the second block section'from the first block section, the rails of said iirst block section being divided into a plurality of track vsectionsjuincluding a first and a second tracksection which are traversed in the order named by 'a'train traveling in the normal direction, a pair of line Wires governedvby traic conditions insaid sec- "ond track section, a, coding relay operated `by coded energy supplied over said line Wiresand controlling the supply of alternating current to the rails of said iirst track sectionymeans gov- "erned by traiii'c conditions' in said second block section for supplying coded alternating current to the rails of said second track section and for supplying coded energyto said line wires, means for supplying feed-back'energy to said linevvires in the intervals between the impulses of energy supplied to said line Wires by the means governed by traffic conditions in said second block section, means for causing the feed-back energy `supplied toV said line Wires lto be of normalor reversel polarity according as said firsttr'acksection is vacant or is occupied, means responsive i.to feed-back energy of normal polarity only supplied over said'line wires for interrupting the supply of energy to said signal lamp, and means responsivel to feed-back energy of either polarity supplied over said line Wires for' preventing the vsupply of alternating current to the rails of said second track section.

- 9. In combination, a stretch of railway'track having track rails divided by insulated 4joints into a first, a second and a third track section nthrough which are operated in the order named locomotives equipped with cab `signal apparatus responsive to the flow of coded alternating current in the track rails, a pair of line wires substantially coextensive with said rsecond and third track sections,a first coding relay controlling the supply of coded alternating current to the rails of said first track section, a second coding relay controlling the supply of coded alternating current to the rails of said second track sec-` tion, means for supplying coded alternating current energy to the rails of said third track section and for supplying coded energy to said line Wires, means effective according as said second section is vacant or is occupied to permit energy to be supplied over said line wires to` said first or said second coding relay, and means effective when said third section is oc.- cupied to prevent the supply of coded energy over said line wires.

10. In a railway signaling system, in combination, a stretch of railroad track divided into a first, a second and a thirdblock section through which are operated in the order named locomotives equipped with 'cab signal apparatus re-` sponsive to the flow of coded alternating current in the section rails, the rails of the second block section being divided in to a plurality of track sections including a first and a second cated at the end of the block section adjacent said third block section, a line circuit governed by traffic conditions in said iirst track section, means governed by traffic` conditions in said third block section for supplying coded alternating current to the rails of said first track section and for supplying coded energy to said line circuit,a rst coding relay controlling the supply of coded alternating current to the rails `of `said rst block section, a second coding relay controlling the supply of coded alternating current to the rails of said second track section, and means effective according as said second track section is vacant or is occupied to connect said linecircuit to said first or said second coding relay. l

11. In a railway signaling system, in combination, a stretch of railway track divided into a` forward anda rearward block section and through which are operated locomotives equipped with cab signal apparatus responsive to the flow of coded alternating current inthe l section rails, the rails ofl said forward block section being divided into' a plurality of` track sections including a forward and a rearward track section, a line circuit governed by traffic conditions in. said forward tracksection, means track section, said first track section being loi.

for supplying'coded alternating current to the rails of said forward track section and for supplying coded energy to said line circuitya first coding relay controlling the supply of coded alternating current to the rails of` said rearward block section, a second coding relay controlling the supply of coded alternating current to the rails of said rearward track section, and means effective according as said second track section is vacant or is occupied to connect said line circuit to said first or said second coding relay.`

12. In a railway signaling system, in combination, a stretch of railway track divided into a forward, an intermediate and a rearward block section and through which are operated locomotives equipped with cab `signal apparatus responsive to flow of coded alternating current in the section rails, the rails of said intermediate, l section being divided into a plurality of track sections including a forward and a rearward i track section, a line circuit governed by traic in said forward track section, a signal includc ing a lamp controlling entrance of trains `into said forward block section, means governed by traffic conditions in said forward block section and controlling a circuit for supplying coded `alternating current to therails of said forward track section and also controlling the supply of coded energy to said line circuit, a rst coding relay controlling the supply of coded alternating current to the rails of said rearward `block section, a second coding relay controlling the supply of coded alternating current` to the rails of said rearward track section, means ef-` fective according as said rearward track section is vacant or is occupied to connect said line circuit to said first or said second coding relay, means associated with said first coding relay `and operative `on the supply of coded energy over i said line circuit to said relay to supply feed-back energy to the line circuit in the intervals between the impulses of energy suppliedr to said line circuit by the` means governed by traffic in said forward block section, and means responsive to feed-back energy supplied over said `line circuit and controlling the supply of energy to said signal lamp.

13. In a railway signaling system, in combination, a stretch of railway track divided into a` forward, `an intermediate and a rearward block section and through which are operated locomoi tives equipped with cab signal apparatus reysponsive to flow of coded alternating current in the section rails, the rails of said intermediate section-being divided into a plurality of track sections including a forward and a rearward `track section, a line circuit governed by 'traino in said forward track section, a signal including a lamp controlling entrance of trains into said forward block section, means governedby traffic` conditions in said forward block sectionV and controlling a circuit for supplying coded alter- `nating current to the rails of said forward track section and also controlling the supply of coded energy to said line circuit, a first coding relay controlling the supply of coded alternating current to the rails of said rearward block section, a second coding relay controlling the supply of coded alternating current tothe rails of said rearward track section, means effective' l according as said rearward track section is vacant or is occupied to connect said line circuit to said first or said second coding relay, :means associated with said first coding relay and `0perative on the supply of coded energy over said line circuit to said relay to supply feed-back` energy to the line circuit in the intervals between the impulses of energy supplied tosaid line circuit by the means governed by trafc in said forward block section, and means responsive to feed-back energy` supplied over said line circuit and controlling the supply of energy to said signal lamp and the circuit forr the rails of supplying alternating current to said forward track section.

CRAWFORD E. STAPLES. f HERMAN G. BLossEa. 

